RDJ's Doom would have to be from Earth-838 (because there is no on-screen confirmation of Tony Stark existing in that world, just a writer's opinion). 616's Dr Strange is responsible for E-838's incursion, as alluded to in Multiverse of Madness.
Could be. I'd like him to be from the FF reality but it doesn't matter, Earth-838 would technically establish him as the Tony Stark of that reality (but technically not Tony either).
Victor Timely's retro-futuristic branched timeline in the 1800s leads to the Fantastic Four's Earth we see in Fantastic Four: First Steps.
Well, that'd make sense. I personally don't think that'll be stated although I do like the idea.
Sentry is the key to stopping Doctor Doom, maybe based on hidden intentions from Valentina that haven't been revealed to us yet.
I do wonder how Sentry will play a role in the film.
Arishem returns to pass judgment on Earth - turns out, Earth is NOT worthy of survival in the grand scheme of the universe; however, Doom bargains with the Celestial in regards to the incoming Incursion to choose between 616, 10005 or the F4's Earth.
Well, Eternals has to be continued eventually.
Ms. Marvel's bands and the Ten Rings are the key to reshaping the timeline from the perspective of the TVA's dimension - Doom has to wipe them all out in order to implement the devices - the bands rewrite history while the Ten Rings hold every timeline in place to prevent branching.
Ah, yes. They did tease that the Ten Rings are important.
The concept of "anchor beings" is a misguided, but not entirely false belief. Paradox's theory was based on how Earth-10005 was dying after Logan's death in 2029. Logan's death wasn't the reason, Monica Rambeau's arrival into that universe, undetected due to the use of the Cosmic Bands, eventually created a paradox effecting how events of Logan will play out and an inevitable Incursion to occur.
Anchor beings are a terrible idea, so any way to eliminate that completely is something I'd take.
All the Kangs, of course, are dead by the time the events of Doomsday occur.
Talk about a sudden dead end. Quantumania was Kang's major moment in the MCU, lol.
Thor dies in Doomsday. Hercules is indirectly responsible. This petty grudge is key to Doom winning.
I think I'd be more surprised if Thor lived through both films than if he didn't.
Spider-Man Brand New Day is grounded, but he still gets the black symbiote as part of his angst arc post-No Way Home. Spider-Man will have the devil on his shoulder while in this state in the form of Frank Castle, who wants Spidey to cut loose against the gangs of New York. Kingpin is dead, this is set after Daredevil Born Again season 2 and Thunderbolts, and the gangs are out trying to fill the power vacuum left behind by Fisk's empire. Knull won't be acknowledged but by the end of the film the symbiote will be destroyed or contained for the future as resolution to that.
...well, I don't like it, but if Kingpin died, I'd be okay with that as long as it's done well. If the MCU keeps going for many years to come, there are going to have to be definitive endings for characters. It's weird to consider, but one day every MCU hero and villain will either retire, die or be forgotten, so it'd be shocking to see Fisk die, but eventually something is going to happen to him one way or the other.